Negotiating and closing contracts

Two ways of saying that a deal has been agreed look almost alike and take different cases. Sich einigen is a reflexive verb, and its pronoun is accusative: Ich habe mich mit dem Käufer geeinigt. Handelseinig werden, like the plainer sich einig werden, is built on an adjective, and adjectives of this kind take a dative reflexive, just as sich sicher sein does: Ich bin mir mit dem Käufer einig. In the plural nothing gives it away, since Wir wurden uns handelseinig reads the same either way. The difference only shows once somebody speaks for themselves, and that is exactly when a wrong mich is heard. Handelseinig also says more than einig: the two sides agree on a sale, on price and terms, not merely on a view. The rest of the list follows a deal from the first exploratory talk to the clause that ends it.